1. Field of the Invention
The invention relates to a semiconductor emission element comprising a plurality of emitting portions on the same substrate and a method of manufacturing the same.
2. Description of the Related Art
Today, various kinds of apparatuses such as an optical disk device, a laser-beam printer, a duplicator and so on using a laser diode (LD) which is a semiconductor emission element, have been developed so far. Recently, a high-speed operation and high performance in each of these apparatuses have been sought, and using a plurality of laser beams is thought to be one method for achieving them. For example, reading speed in an optical disk device can be easily made faster through simultaneously reading a plurality of tracks using a plurality of laser beams. Accordingly, developing a semiconductor laser (that is, multi-beam laser) which is able to simultaneously emit a plurality of laser beams has been required.
FIG. 1 shows a disassembled configuration of a multi-beam laser of the related art. The multibeam laser 100 comprises four laser oscillators 120 formed on the same substrate 111, and each contact electrode 181 formed respectively on a base 180 through each wire 182 is electrically connected to each electrode 115. However not shown in the figure, each wire connecting portion for connecting an electrode through each wire is respectively provided in each of the wires 182. Each of the laser oscillators 120 are respectively connected to power source (not shown in figure) through each wire 182 being respectively connected to each of the wire connecting portions.
When manufacturing such a multi-beam laser, first, each of the laser oscillators 120 is respectively formed on the substrate 111. Next, apart from that, each of the contact electrodes 181 are am respectively formed in the base 180 before respectively connecting each of the laser oscillators 120 formed in the substrate 111 and each of the contact electrodes 181 formed in the base 180 to each other. Accordingly, there is a problem with this multi-beam laser that mass production is difficult since alignment of the position of each of the laser oscillators 120 and each of the contact electrodes 181 becomes difficult when the spaces between each of the laser oscillators 120 become extremely narrow. Recently, an idea of placing the substrate 111 to the base 180 with the laser oscillator 120 side of the substrate 111 placed towards the opposite side of the base 180 has been considered. A multi-beam laser can be easily manufactured without having a problem in alignment of the position if the substrate 111 is made to be supported by the base 180 as described.
However, on the other hand, in a case where the laser oscillator 120 side of the substrate 111 is placed towards the opposite side of the base 180, radiation of heat generated in each of the laser oscillators 120 becomes more difficult comparing to a case of the related art. For example, in a case where the laser oscillator 120 side of the substrate 111 is placed towards the base 180 side as the related art, the base 180 can serve a radiating function by forming it with a material with high thermal conductivity such as aluminum nitride (AIN) so that heat generated in each of the laser oscillators 120 can be actively radiated through the base 180. In contrast, in a case where the laser oscillator 120 side of the substrate 111 is placed towards the opposite side of the base 180, the distance between the laser oscillator 120 and the base 180 becomes further so that the radiating function of the base 180 can not be expected. Accordingly, in a case where the laser oscillator 120 side of the substrate 111 is placed towards the opposite side of the base 180, there is a problem that threshold current of each of the laser oscillators 120 is increased and the emission power is decreased unless radiation of heat is encouraged in someways.
The invention is designed to overcome the foregoing problems. It is an object to provide a semiconductor emission element which is able to be easily manufactured while encouraging radiation and a method of manufacturing the same.
A semiconductor emission element of the invention comprises: a base; a substrate supported by the base; a plurality of emitting portions each composed of a plurality of semiconductor layers which are formed by being laminated on the opposite side of the base of the substrate; a plurality of ohmic electrodes respectively provided on the opposite side of the substrate by corresponding to each of the emitting portion while being electrically connected to each of the emitting portion; and at least one radiation layer formed on the ohmic electrodes.
A method of manufacturing a semiconductor emission element of the invention includes the steps of: respectively forming a plurality of emitting portion each made of a plurality of semiconductor layers which area formed by being laminated on a substrate; respectively forming a plurality of ohmic electrodes on each of the emitting portion, which are electrically connected by being corresponded thereto; forming at least one radiation layer on the ohmic electrodes; and supporting the substrate by a base by making the base face the opposite side of the emitting portion of the substrate.
In the semiconductor emission element of the invention, an electric current is flowed into each of the emitting portion through each of the ohmic electrodes and emission occurs in the emitting portion. At this time, generation of heat occurs in the emitting portion, however, the generated heat is actively radiated by a radiation layer. As a result, influence by generation of heat is eliminated and deterioration of the performance of the emitting portion is suppressed.
In a method of manufacturing a semiconductor emission element of the invention, a plurality of emitting portions respectively made of a plurality of semiconductor layers formed by being laminated on a substrate are respectively formed. Further, a plurality of ohmic electrodes are respectively formed on the substrate of each of the emitting portion while at least one radiation layer is formed on the emitting portions. Further, the substrate is supported by a base by making the base face the opposite side of the emitting portions of the substrate.